It sounds like the main thing interfering with strategies right now isn't the outright difficulty of the monsters, but how much those monsters want to aggro when it really feels like they shouldn't. In the other thread, someone even mentions splitting into three groups of 12 and fighting all three monsters at once to deal with this oddity.

It sounds like Legion would be a much easier event to handle if the aggro ranges were shorter or less wonky. Particularly since "this thing comes running with a hungry look in it's eyes and murder in it's heart from four miles off" is an ability we have no specific counter-measure (such as Earthen Armor for extremely damaging abilities) for at present.